platform/x86/amd/pmf: Fix a missing cleanup path

platform/x86/amd/pmf: Fix a missing cleanup path

On systems that support slider notifications but don't otherwise support
granular slider the SPS cleanup path doesn't run.

This means that loading/unloading/loading leads to failures because
the sysfs files don't get setup properly when reloaded.

Add the missing cleanup path.

Fixes: 33c9ab5b493a ("platform/x86/amd/pmf: Notify OS power slider update")
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Link: https://lore.kernel.org/r/20230823185421.23959-1-mario.limonciello@amd.com
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>